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Updated: 2012 Apr 18, 22:08 UT
Event Rank : 97
(The event Rank is a measure of the likelihood of observing an event, and is equal to the probability of at least one successful observation by a team of two observers spaced 1/8 path width just inside opposite sides of the predicted path. An event rank of 100 indicates that the prediction is expected to be very accurate).
THE UPDATED PATH
Note: The duration given in the line below is the interval during which the occultation shadow sweeps across the Earth - please see the minute markers on the map to determine the approximate time for your location.
On 2012 Apr 22 UT, the 108 km diameter asteroid (203) Pompeja will occult a 10.5 mag star in the constellation Gemini for observers along a path across New Zealand, running from Westport to Kaikoura.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.8 mag to 14.2 mag (the magnitude of the asteroid) for at most 3.8 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC.
Additional details of this and other events are available at Steve Preston's website at http://www.asteroidoccultation.com/
EVENT DETAILS SUMMARY :Important Note regarding Accuracy:
The uncertainty interval in path widths given above (and shown as a 1-sigma uncertainty ellipse on the plot) refers to RMS deviation and is applied as a +/- range. In other words, a path uncertainty of 1.0 path widths means that the actual center of the asteroid's shadow path should fall within plus or minus 1 path width of the plotted path center. However path errors larger than 1 sigma have been observed so observers should be alert for primary occultations within plus or minus 3 sigma of the updated path.
Further, almost all asteroidal satellites discovered so far have been found within 10 diameters of the asteroid (since this distance is deep enough within the gravitational well to be stable over long timescales). Therefore, if monitoring for secondary events, observing out to about 10 path-widths either side of the predicted track remains worthwhile.
We therefore recommend that you monitor for events if your observing location is up to +/- 10 path-widths from the predicted track. If not monitoring for occultations by secondary bodies you should observe from locations within 3 sigma of the nominal path.
In terms of time, the predictions are now usually accurate to about +/- 0.3 minute so you should be most attentive during the predicted minute of the event. However if intending to catch a potential satellite occultation you should start observing at least 10 times the predicted central duration before the predicted closest approach time for your location, and continue for a similar period afterwards.
Occultation of TYC 1884-01092-1 by 203 Pompeja on 2012 Apr 22
Centre Star Star Sun Path Limits Error Limits
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
176 38 32 -44 0 0 7 53 54 9 319 -27 174 54 17 178 21 6 173 31 41 179 40 3
174 51 22 -43 0 0 7 53 52 11 321 -26 173 6 58 176 33 56 171 44 9 177 52 49
173 2 54 -42 0 0 7 53 50 13 322 -24 171 18 8 174 45 42 169 54 55 176 4 40
171 12 52 -41 0 0 7 53 47 14 323 -23 169 27 29 172 56 8 168 3 39 174 15 20
169 20 57 -40 0 0 7 53 45 16 325 -22 167 34 40 171 4 55 166 9 58 172 24 33
167 26 47 -39 0 0 7 53 42 18 326 -20 165 39 18 169 11 44 164 13 30 170 32 0
165 29 59 -38 0 0 7 53 38 19 327 -19 163 40 57 167 16 13 162 13 44 168 37 20
163 30 6 -37 0 0 7 53 34 21 329 -17 161 39 6 165 17 58 160 10 6 166 40 11
161 26 34 -36 0 0 7 53 30 23 331 -15 159 33 8 163 16 30 158 1 54 164 40 6
160 0 0 -35 19 7 7 53 26 24 332 -14 -36 12 37 -34 26 46 -36 55 12 -33 46 39
159 0 0 -34 51 23 7 53 24 25 333 -13 -35 44 35 -33 59 18 -36 26 54 -33 19 24
158 0 0 -34 24 8 7 53 22 25 333 -12 -35 17 3 -33 32 20 -35 59 8 -32 52 38
157 0 0 -33 57 24 7 53 19 26 334 -12 -34 50 1 -33 5 52 -35 31 52 -32 26 22
156 0 0 -33 31 12 7 53 17 27 335 -11 -34 23 32 -32 39 56 -35 5 9 -32 0 37
155 0 0 -33 5 31 7 53 14 28 336 -10 -33 57 35 -32 14 31 -34 38 58 -31 35 24
154 0 0 -32 40 23 7 53 11 28 337 -9 -33 32 11 -31 49 38 -34 13 20 -31 10 43
153 0 0 -32 15 49 7 53 9 29 338 -8 -33 7 20 -31 25 18 -33 48 17 -30 46 34
152 0 0 -31 51 48 7 53 6 30 339 -7 -32 43 4 -31 1 32 -33 23 48 -30 22 59
151 0 0 -31 28 22 7 53 3 30 339 -6 -32 19 23 -30 38 20 -32 59 54 -29 59 57
150 0 0 -31 5 31 7 53 0 31 340 -5 -31 56 17 -30 15 43 -32 36 36 -29 37 30
Uncertainty in time = +/- 2 secs
Prediction of 2012 Apr 19.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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